Perhaps 2017 might be remembered as the first holiday season when at-home genetic testing kits received the same billing as the latest version of Amazon’s electronic assistant Alexa. These kits, which allow consumers to submit a saliva sample via mail and have their DNA sequenced, were a big seller during the four days between Black Friday and Cyber Monday this year. The popular testing company Ancestry sold more than 1.5 million kits, according to its website.

As the kits become more ubiquitous, two leading companies in this space, 23andMe and Ancestry, don’t hesitate to play up the gift-giving angle on their websites. “‘Tis the season! Give the gift of discovery,” reads one advertisement on 23andMe’s landing page. Ancestry promotes its holiday sale with special three-for-one pricing. (Since they first appeared on the market a decade ago, the cost for some of these tests has dropped from hundreds of dollars to the equivalent of half a year’s subscription to Netflix.) And it seems to be working: O Magazine listed 23andMe’s kit as “One of Oprah’s Favorite Things.”

At least half a dozen well-established consumer DNA testing companies operate according to one similar model: a consumer buys a kit (ranging from $70 to $200), collects a saliva sample, returns the kit to the company in a prepaid mailer, and receives online access to explore the DNA results. Some test makers claim that customers’ DNA samples can reveal everything from their ethnic roots, to how they metabolize caffeine, to their odds for developing Parkinson’s disease.

As the popularity of these genetic testing kits has increased, so has awareness in the medical community of the need to better inform consumers about the limitations of the kits. Two Yale Medicine experts break down the pros and cons offered by these tests.

PROS:

As long as consumers are aware of potential risks, which not only includes the possibility of learning about worrisome health information but also awareness that companies store the data for internal research, then getting such a kit as a gift could be fun, says Michele Spencer-Manzon, MD, assistant professor of genetics and of pediatrics at Yale School of Medicine.

“I think it’s the kind of gift you should only buy for someone whose preferences you know well,” Dr. Spencer-Manzon says. If you purchase one of these kits for someone, a person on the receiving end can always decide not to submit a DNA sample, she adds. “I wouldn’t send in someone’s kit for them and surprise them,” she cautions.

Dr. Spencer-Manzon points out that different companies provide different sorts of information. “The Ancestry kit that focuses only on ethnic backgrounds is fun—I know geneticists who have done them—and I don’t think there are any downsides to that,” she says.

One geneticist considering such testing is Lauren Jeffries, DO, the clinical genetics coordinator at Yale Medicine’s Pediatric Genomics Discovery Program. “I have been interested in expanding my family tree, and so I would choose a company that gives specific details about ancestry,” Dr. Jeffries says.

CONS:

Both geneticists agreed that all genetic testing companies have privacy and consent rules that need to be read carefully and that it is vitally important for consumers to be aware of marketing gimmicks.

For example, 23andMe states on its website that its DNA collection kit is “FDA-cleared for use with our Genetic Health Risk and Carrier Status reports.” But the Food and Drug Administration (FDA) does not regulate genetic tests, Dr. Spencer-Manzon explains. In April, the administration announced that it would allow 23andMe to advertise and market directly to consumers about its “genetic health risk” tests for 10 diseases or conditions. “What this means is that the FDA allows 23andMe to share information about the risks of testing and of receiving results, and that there is no known harm that can come from collecting saliva,” Dr. Spencer-Mazon says. But the tests are not validated for clinical use, she adds. “This means there’s no information you could get out of the results that could be clinically actionable items.”

“Any DNA test you can order for yourself from home falls into a category I’ve been calling ‘curiosity genetics,’” Dr. Jeffries says. The results can be conversation starters with friends and family, but anyone with a specific heritable health concern should visit a genetics professional, she says.

Dr. Jeffries finds two aspects of the tests worrisome. The first relates to privacy, “as online data theft becomes more prevalent.” Second, she is concerned about a potential lack of appropriate counseling before and after a person receives the test results. Both physicians explain that so many factors go into deciding a patient’s risk related to genetic diseases and conditions that a mail-order kit cannot take into consideration.

For her part, Dr. Spencer-Manzon worries about consumers who learn that they may have a decreased risk for a certain disease or condition and may interpret this to mean they won’t have to worry about that aspect of their health. “So many factors must be considered,” Dr. Spencer-Manzon says. “We are learning new things about genetics each day.”

Meanwhile, there’s still much we don’t know about the impact that knowledge gleaned from a genetic test result might have on a person’s psychology. In a study published earlier this year by Yale researchers, participants who were told they had a gene that predisposed them to depression were more likely to report they had experienced a period of major depression than those who were told they lacked the gene. (In both cases, the information was fictitious, as the researchers did not sequence the participants’ genes.)

In the end, neither geneticist would recommend a particular brand of the DNA testing kits. If a person is curious about tracing family roots back several centuries, then the tests could be fun, Dr. Spencer-Manzon says. But, it’s risky to engage in any genetic testing without some form of professional genetic counseling, Dr. Jeffries says.

“If someone is concerned about a disease, they should see a physician, nurse practitioner or genetic counselor about their concerns,” Dr. Spencer-Manzon says.